Process of tanning hides



Patented Jan. 1935 I UNITED STATE v I I 1 ,988,684 v mosses eame .,,,H on M qg uorf, Indianapolis, Ind.

. No ,,Drawing. Application November 17, 1 9 32, I

Serial No. 643,053; Renewed April1 2,.1934

7 claims. (01. 149 -4)" This invention relates to the :art of tanning and completely... through. the hide, completely leathers and particularly to a method decreasing tanning the hide. to give as good if not better the length of timerequired heretofore in the leather'than heretofore obtained. in the longer, tanning operation. Heretofore, the ..customary step by step, processeof going from, tanning ma- 5 method has been to prepare the raw hides by terials of increasing strengths.

removing theforeign matter suchas hair, dirt, In otherwords, I employ what I believe to be grease, loose flesh and the like all in the usual purelya mechanical processwhereinthe fibers manner .well known to those versed in the art. of the leather are first completely coated with The hides were than immersed in tanning films of protectivematerial having less surface liquors beginning first with a veryweak liquor tension than a water tanningv solution and a 10 in respect, to the: tanning agent and. then specific gravity,.-.lessthan waterxso that when gradually increasing .thestrength of'the liquor. the .hidecontaining this material is submerged Sufilcient time had to. elapse to. permit the weakin a water solution of the tanning .material this er liquor to thorougmy penetrate the hide beprotective'material will tend to ,-gradua;lly.-l'eave fore the next stronger liquor could be employed. the hide by reasonof the differences in, specific If this. process was speeded up toshorten the gravi a permit adual replacemen intervals of time between the applications of therewith of the tanning material; S o t, my the succeeding, increasing strengths,v the hides invent ql c ntempla e taking thev hide'wh h were damaged so that. first class leather could has ee pr v u ly p par d f ta n ns, giving not be produced. Inemploying thisusual procit a treatment with a pro c v m erial firs essi of subjecting t the .hides.:to increasing holding out all of. the tanning materialsand strengths of liquor, the time required was genthen g u ly ep the protective material erally in the neighborhood of from seven to y he tanning materials as determined by t -twentyefive. days. Werethe hide to beplaced e wh ch the pmtectivemaqe e leaves the atxonce in .the strongest liquor,.l it would become hide... T rate d t rmined by the differences damaged to 81101123111 extent .as to become practisu a tension pe fi rav y Of-th callyunusable. j 1 I t protective material and the. tanning ,material This process heretofore employed is. one re- S01llti0nr quiring considerable;attention and must be The nvention will be betterunderstood by T watched closely to insure that the fibers of the scribing one particular way in carrying-. out the 30 hide do not becomedamaged by too ra id-subpr s 'I t t h d s a er theyhavebeen jection to the stronger :liquors. It is essentialln nitial y p epa d f ni ln t u ual man- .any processthat thetanning materials be, uni- 'n rbutinstead of t en bj t 'th des to formly and thoroughly distribtitedthrough the nn n materials, d op them inavat contain- .v hideto around the'fiberstherein'. i s he p t ve-material .1to..be employ 35 By my invention I have been-ableto. increase One particular p o t material Q I find thespeed with which the tanning materialswill to work, v ry successfully s solvent naphtha in penetrate and completely. tan a hide without hecrudelvform as distilledzfrom coal tar havin damage thereto. My method .consists essentialthe approximateconstants, .862; to ".892 .specificz' 1y. of using a liquid material non-injurious to the eravlty,:. 60. d es C boiling point D 40 .,hide fibers which has. a 'quick and thorough cent) and a flash pointofabout25.6 degrees C. penetrating action on the raw prepared hide so The refined form may be used without noticeable as to have this material penetrate' and fill: all 7 difference in the results. ,An essential quality of of the minute interstices within'thehide and the protective material is that. it be a liquid! coat the surfaces of the fibers therein, giving ficapableof readily forming. films about the-hide the hide-a solid and .plump appearance, followfibers :andhave a surface tension slightly less ing which step the; hide'thus treated is sub- ,thanthat of water films. The hide will be very :merged in a ta'nningliquor of the finalstrength shortly completely penetrated by the; material to be employed, or-at least of a'stren gth much employed, with the/airand water driven out: greater than that which 'hasheretoforebeen from between the fibers and adhering films of possible tcruse on the rawhides, Withina relathe material formed therearound as wellas filltively-short. time, the, penetrating material' ing the interstices between the fibers. ,After initially employed will be found floating on the the hides have been' thoroughly penetrated :by surface of the tanning material and the tanning 7 this material the 1 hides thus treated are re-i. material found to have penetrated uniformly moved from this protective material bath and submergedina vat containing the tanning material. This tanning material is in the form of a solution of the'customary wood and bark in water but has a strength equal to that ordinarily employed as the strength in the last step of the process heretofore employed, the permissible strength being as high as 80 degrees, barkometer. The hides are left in this tanning vat until the tanning material has completely penetrated the hides and displaced the protective material itself. .tperiodofxtime willivary depend n upon the thickness of the hides.

When the hides are placed in the protective material, they are submerged therein and a rapid ebullition of air is at once observed,"indioating that the protective material is passing to .yv-ithin the hides to displace the air which has be n entrapped therein. When' t he hides treated with this material are placed in the tanning-solution, the hides are submerged and an accumulation of the protective material is soon observed floatingon the .topiof.. this: solution." 135 1636011 of 'the fact that ithe hides varensubmerged and false ofathe fact that the Idifierence inxspecific gravity -of--thisiprotectivelimaterial:andof. the .water tanning solution, thetprotective xmaterial willleave the hid'eslfn'oii too rapidlybutgradually and contin uously, .an'dlas itzzdoes' sog. the tanning. solution will of: courseflow in' to replace: this material as it.- leaves. 'Whenithe'interchangeof these mate,-

ria-ls is I'complete, t the :hides are thoroughly tannediiandl-areitaken-mom the. vat: to be subje'cted' to further conditioning I treatment as is --the usual praotice.

3 5 The protective material initially 'holds -back the- -strong tanning solution -so= as uto prevent burning ofi the'-fib'ers, and the tanning solution '-"is onlyadmitted--to =thexfibers; as the protective mait'erial leaves'. LThe .rateof; interchange seems 40 to be ideal in that the fiberstare uniformly subje'c'ted to a gradually increasing amount of the tanning solution at just theiright speed togive ai thor'ough tanningwithout drawingand burning th hides.

l believe -thatwhat actually occurs in prac- -ticing my invehtiofn is te-be explained as follows. hides :as; initially prepared-for tanning are 11111 of water and contairr some air. When the hides are immersed in the liquid protective'mat teri'al whieh does' not diffuse in -water and has Ie'ss s'urfa'ce-tensiorr tha1i thataofwater, the

- pl'a'0'ed by the protective liquid films so. asto com pl'etely encloselt-hem. Ihemwhenthe hides -thus protected are-submerged irr the math of ts/mung liquor ha ving water as the: solvent; as between thesurface tension of- 'themroteetive -materi'al andof theliquor, the protective materialtends to rem'ain; but -beingsubmerged; its

-'applied towhat air may be within the fibers; the protective 1 material 5 thus cleaves the fibersnot tive material: become :thinnen and thinner until 111: increasingly larger-quantities .until -.the =re- "-the-water films. F-I'lhere is-'' the further' possi-ble action-g in th t aneprotectivediqiiid initially displ air from,

-'- the-time'stillfighting against gravity to displace when the protected hides are submerged in the water tanning solution, the surface tensions then to be considered are those of the protective liquid, the tanning liquid and the solid fibers. By eliminating the air, then the surface tensions between the air and liquid and between the air and Water are eliminated, leaving but the surface tension between the liquid and the water. The situation arises where two liquids are in contact in the absence of air but ,adjacerrt solid ibersin. whic r ase aliqiid wi hm r in the direction in which the surface-pressure at the solid is least, and since the protective liquid is adjacent the fiber when the tanning liquor is *applie'd,-"then"-the tanning liquor would drive or .fel ase the ;pr otective fluid along and off the fibers to allow the tanning liquors to come into Contact gradu ally withthe fibers.

In followi-ngthe above process in accordance With my invention, the raw hide is completely tanned within a much shorter period than permissible ,-.with= thejtmethodi heretofore. .employed. ,Inflcomparison, :I have :found in tanninglike hides, that,:for,a hidezof, approximately ;1/12-.of an: inch; thickness; the, .old methodi-has required 'pfromfivexto six-.daysto completely tan thefibers, cwhereas' .by. my'invention', theesame result is. .ob-

vtainedin from: 12:..to 24shours. rT-his-decreasein .timelrequiredi for tanning; is,-not.-secured;at1 the expense ofi alower-qualityof leather .butinstead :I find that theleathen tanned .by this new .proc- --materi'al= .by ithe. ,tanning. .materia1,-. andrthatthe :,-invention isinothlimitedzlto the-particular han- -dling.herein. .set-out.' 3

I-tclaim:.

1.;In :the: processnf tanning hides; the .com-

- ofpreparing' the hides-for .tanning; :the-step of immersing the prepared hides in adiqu-id .pro- -tective materiaLh-aving. auspecific gravityidifieri-nglfrom that of'ai water solution-of tanningma- A V o terial tonbe employed to.secure a,thorough ipene-' water fi lms sboutthe hide fibers'are rapidly retratiom of the material through the hides, and the step. 'of then immersingithe hides. in a. bath --of=' relatively. strong. water. .solution of tanning :material and. retaining the. hides in the .bath un- H til the tanningsolutionalhas. displaced theVpro- .--tective mate1 ial.

2: I he-v method .of .tanning =hides which. in- -fcludes initially preparing the. hides. for. tanning,

immersing andxetainingl theprep'ared hidesin a sol'vent .naphthamathiuntil the-hides. are .thor-' oughlylpenetrated gthereby, and: then immersing andretain-ingrthe.hides in av bath. of a-water viole'1 itly but gr'adue tlly since the net operating a i 4 forces are relatively small. The films of =protecsolutionohtanning; materials until .the solvent naph'tha .isreplacediby the tanning. material Y resolution. they puncture and permit the tanning liquorto breal: through-in small quantities firstpand then 3: 'Il1e-method\ otitanning ;hides.-which..ineludes initially preparing the. hides for. tanning,

soaking E-th'e hides in a protectivemateriallighter placement is complete; theprotective =films all than thesolution of-tanning-material-to be employed until= the material has -thoroughly pene "trated -the I hides; a and I then i flowing out 1 that -'-protective--material in-- wate1=--in the presence -of a relatively strongconcentration-"ofttanning 'ma-terials'.

a bination of .those steps .whichcomprise thestep 4. The method of tanning hides which comprises initially preparing the hides for tanning, coating the fibers in the hides with films of a protective liquid having a surface tension slightly less than that of water, and then replacing those films with films of a water solution of tanning materials, and applying pressure to the hides to accelerate the rate of replacement of said liquid films by the water films. I

5. The method of tanning hides which comprises initially preparing the hides to leave films of water about the fibers in the hide in the presence of air, subjecting the water films in the presence of the air to films of a protective liquid having a surface tension between it and the water film less than the sum of the surface tensions between the air and the water, and the air and the liquid whereby the water films are replaced by protective liquid films, filling the voids between the fibersiin the hides with the protective liquid to expel the air, floating out the protective liquid from the voids in the hides in the absence of air and in the presence of a water tanning solution wherein the surface tension of the tanning solution is less than that of the surface tension of the protective liquid,

and continuing the application of the tanning solution to the hides to cause a displacement of the protective liquid fihns by films of the tanning solution.

6, In the process of tanning hides, the combination of those steps which consist of the step of treating the. hides with. a liquid, water insoluble, protective penetrating material having a specific gravity less than that of the tanning solution to be employed to fill the voids and coat the fibers in the hides, and the following step of interchanging that protective material with the tanning solution by relative flows of the materialand the solution induced by differences in specific gravities and surface tensions therebetween. i f

7. In a method of treating a hide wherein the hide is subjected to a tanning liquor, those steps which include the step of immersing the hide immediately preceding the application of the tanning liquor thereto in an oil having more surface tension than that of the liquor, and the succeeding step of immersing the oil plumped hide in the liquor to permit an interchange of the liquor with the oil. v

' HAROLD M. GUSDORF.

CERTIFICATE OF CORRETION.

Patent No. 1,988, 684 January 22, 1935.

HAROLD M. GUSDORF.

ii is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as foliows: Page 1, second column, line ll), for "a water tanning solution" read water; and line 11, for "water" read a water tanning solution; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of May. A. D. 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

